Assessing comorbidity in older adults using prescription claims data
Corresponding Author
Marie-France Dubois
Department of Community Health Sciences, Faculty of Medicine and Health Sciences, Université de Sherbrooke,
Research Centre on Aging, Sherbrooke,
Marie-France Dubois, Department of Community Health Sciences, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Qc, Canada J1H 5N4.E-mail: [email protected]Search for more papers by this authorNicole Dubuc
Research Centre on Aging, Sherbrooke,
School of Nursing, Faculty of Medicine and Health Sciences, Université de Sherbrooke,
Search for more papers by this authorEdeltraut Kröger
Centre d'excellence sur le vieillissement de Québec, Centre de recherche affilié universitaire de Québec, Hôpital St-Sacrement,
Search for more papers by this authorRéjean Hébert
Research Centre on Aging, Sherbrooke,
Department of Family Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Québec, Canada
Search for more papers by this authorCorresponding Author
Marie-France Dubois
Department of Community Health Sciences, Faculty of Medicine and Health Sciences, Université de Sherbrooke,
Research Centre on Aging, Sherbrooke,
Marie-France Dubois, Department of Community Health Sciences, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Qc, Canada J1H 5N4.E-mail: [email protected]Search for more papers by this authorNicole Dubuc
Research Centre on Aging, Sherbrooke,
School of Nursing, Faculty of Medicine and Health Sciences, Université de Sherbrooke,
Search for more papers by this authorEdeltraut Kröger
Centre d'excellence sur le vieillissement de Québec, Centre de recherche affilié universitaire de Québec, Hôpital St-Sacrement,
Search for more papers by this authorRéjean Hébert
Research Centre on Aging, Sherbrooke,
Department of Family Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Québec, Canada
Search for more papers by this authorAbstract
Objectives Comorbidity is an important confounder in many studies. Since self-reports, medical records abstraction and medical claims databases present problems of practicability, comorbidity scores can be derived more conveniently from prescription claims databases. Existing scores were developed for people aged 18 years or older and use costs, hospitalizations or death as outcomes of interest. Therefore, they tend to be of limited value when studying disability in older adults. Our objective was to develop the Chronic Disease Score for Disability in Older Adults (CDS-DOA) based on outpatient prescription claims data from community pharmacies.
Methods Clark et al.'s 1995 extended Chronic Disease Score was revised and expanded to account for diseases and treatments relevant for older adults. Empirical weights for frail older adults were then derived on a development sample (n= 1000) using a multiple regression model with disability as the outcome. Beta coefficients were used to weight the CDS-DOA, which was then assessed in a validation sample (n= 402). Year-to-year stability of the CDS-DOA was appraised as well as its construct validity through associations with known correlates of comorbidity.
Key findings The CDS-DOA explained 12–16% of the variance in disability, in both the development and validation samples. It showed high year-to-year stability (intraclass correlation coefficient = 0.74) and was associated with every examined correlate of comorbidity (P < 0.01).
Conclusions The CDS-DOA is a valid and stable comorbidity score in community-dwelling frail older adults and may be used for adjustment in epidemiological studies of disability using prescription claims data.
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